The present invention relates to a method and apparatus for forming a non-woven web by deposition of synthetic filaments upon an advancing deposit felt.
In the manufacturing process of a non-woven web out of synthetic fibers or filaments, a plurality of extruded filament strands have to be deposited to form a textile web as evenly as possible. The filament strands are drawn off using a feed fluid more or less after the extrusion and cool-down processes and guided to a deposit belt. For example, a generic method and also a generic apparatus are described in the U.S. Pat. No. 6,183,684, where a drawing unit is used in order to pull off the synthetic filaments from a spinneret after the extrusion process, and then draw and deposit them. For this purpose, the drawing unit comprises a guide channel that has a slot-shaped filament inlet on its top side and a slot-shaped filament outlet on its lower side. Just below the filament inlet, several fluid inlets meet the guiding channel through which a feed fluid is supplied to the guide channel under the effect of an over-pressure. Due to this, the filament strands are pulled into the drawing unit and accelerated inside the guide channel and blown out through the filament outlet as a filament stream. A drawing process of the filament strands takes place simultaneously, after which the filaments are immediately collected by a deposit belt for deposit. The filaments impact on the deposit belt together with the feed fluid as a filament stream in an essentially vertical manner.
The known method and the known apparatus have proved to be especially useful to be able to generate high rates of production where the filament strands can attain speeds of up to 8,000 m/min. The filament stream generated by the drawing unit thus meets the surface of the deposit belt with relatively high energy. As a result, the individual filaments tend to get interlocked on the surface of the deposit belt.
It is an object of the present invention to provide a method and an apparatus for depositing filaments at high speeds of the generic type in which a more reliable discharge of the non-woven web from the deposit belt is ensured.